That's not true...
It doesn't fall under redistribution, or reissuing without permission - in no way is it illegal or against any of the copyright acts to privately share files, even without the author knowing (I have to know this as I am a musical artist). It may be against the author's will, but in that case, it is only merely like modding GTA V - Take Two hate it, but it's not a crime.
And even so, if it is shared as a bootlegged version, or and edited version, that is not illegal anyway - and as if anybody creating OMSI content is going to be sad enough to have paid for copyrighting rights and permissions.
It is just a game, after all. Nobody is going to care, let alone break your door down.